I live in GRB. I don't know the specific information that the flight crew/dispatch was looking at. That being said, GRB is a relatively quiet Charlie airport. The last scheduled flight arrived at about 2315L the night before. The first scheduled departure isn't until like 5am. I'm not sure if there were any braking action reports between 2315 and the incident. Maybe when GRB got notification of the diversion, they had an ops guy go out and do a braking test. I don't know. All I do know is the rain/freezing rain that night was pretty heavy. I had to close my bedroom window for noise, I had a hard time getting my car started the next day (probably because of water in the line), and I could have went ice skating on my apartment's parking lot. The actual conditions obviously deteriorated from whatever the last reports were. No company or pilot is going to dispatch an aircraft to an airport with the intention of overrunning the runway. Accidents happen, and I'm just glad to hear that no one was hurt.
Like I said. I don't know if/when the braking action report was generated. If there was a recent report, disregard my rambling. But how do we prevent this in the future? When a quiet airport gets notification of a diversion at an odd hour of the night, wake up farmer Joe and have him go drag racing on the runway a few times with the airport SUV.